Suzuki GSX-R 750 Motorcycle Engine In Race Car

[propuckstopper]

Hi folks. I hope all is well. I'll try not to make this the typical "what kind of oil should I use" thread.

After a ten year hiatus from Mini-Sprint racing, I will be returning to competition later this year. I have a bone stock 2007 Suzuki GSX-R 750 engine going into the car. I will use genuine Suzuki oil filters.

Ten years ago, I used Valvoline 20W-50 Racing Formula and changed it after every night of racing. This may have been a little extreme, but it made me happy and kept the engine alive for four unbelievable years without a rebuild.

Now, the Suzuki owner's manual I bought with the engine states to use 10W-40. I will be using both Amsoil Motorcycle Formula and/or Mobil 1 Racing Formula in this engine.

My questions are:
1. Can I get away with a little longer OCI's than I did 10 years ago? How long would you go?

2. Would you stick with the recommended viscosity of 10W-40, or should I go to 20W-50?

Keep in mind that while installed in a Mini Sprint, this engine will be run full throttle for as much as five minutes at a time. Car weight is about 725 pounds, so that is about 300 pounds more than the engine would have to haul around if it remained in the original motorcycle.

Looking forward to your expert opinions!

 

[Audi Junkie]

Just off-hand...Mobil 1 10w-40 Hi-Miles, if you want synth. If going dino, 15w-40 should and does offer higher HT/HS than most 10w-40. Valvoline VR-1 is another to consider, but you might end up with as good or better result with 15w-40 under your conditions. How long is a race anyway and what part of the powerband will you use? I'd strongly consider Used Oil Analysis as part of your programme.

Most bikers here use Rotella 15w-40, including me in my 1991 GSX-F 750. I have Shell 20w-50 in for now, mid-summer, but Rotella 5w-40 Synth is another to consider.

BTW- will you retain the wet clutch and gearset?

 

[propuckstopper]

Thanks for the reply! Yes, this engine will remain stock down to the wet clutch and gearset. A race can be as much as 20 laps under full throttle at about 14,800 RPM.

Hope this helps!

 

[sunruh]

if it were me and i'll write this as if it was:

oil is cheap to change. parts are expensive to replace.

i would stick with the same oci as before.

and Valvoline VR1 is one of the few oils i would trust as well. a good choice in my book. if you could run the sae40 or sae30 (straight weights) instead of the 20w50 i might consider that as well.

did you ever do a uoa to see how whipped it was?

 

[propuckstopper]

Back in the 1990s, I never did an OCI to see how the oil was. Because I was changing it every race (and it was sponsored), I didn't really think it was necessary.

Now that the oil won't be sponsored and synthetic motorcycle is not cheap, I was curious if I could extend the OCI.

 

[XS650]

That sounds like some pretty rough duty.

Try one race on the first batch of oil, get a UOA, then decide how long to run it the next time.

If you want to save some money and your oil temps are staying under 270F, (which I doubt unless you have a generous sized oil cooler) then a good HDEO 15W-40 should do the trick for a lot less money. You can probably get more than one race out of an HDEO too, a UOA will tell.

 

[TucsonDon]

Originally Posted By: propuckstopper
A race can be as much as 20 laps under full throttle at about 14,800 RPM.

Ouch! If anything will stress an oil, that will.

 

[Steve S]

The guy that does my smog tests has one, they are really cool.

 

[gusgeds]

Hi,i am involved in sprints and speed hill climbing in the uk.We run cars such as Jedi,OMS and Force all with bike engines ranging from 250bhp hayabusas to almost stock blackbirds and blades.
The big thing in bike engined cars is copeing with oil surge if you are not running a dry sump setup and also the gear box/clutch is having to cope with more weight than it would originally and the wet clutch is really stressed what with wide sticky slick tyres and no cush drive.

For that reason it makes sense to run a bike specific oil because of the JASO MA spec to cope with the wet clutch and also many of the bike specific oils have a EP content to protect dog rings and gears operating outside the role they are designed for.---I never ceased to be amazed by the abuse modern bike units can stick.
Popular brands here are Shell advance ultra 10/40,Castrol power 1 10/40 and Silkolene 10/50 and Mobil 1 15/50.Just to my mind it makes sense to use a synthetic bike specific oil and change it every few events.Remember the likes of Shell etc put in a lot of r&d into these products,best wishes gus.